This invention relates generally to battery chargers and specifically to battery chargers for charging a battery or a battery pack from a conventional 12 volt automobile battery.
There are many well-known battery chargers in use, including those that operate by plugging into the cigarette lighter of an automobile, or other suitably equipped vehicle, and drawing power from the vehicle battery for either charging another automobile battery in a lesser state of charge or for recharging other type batteries such as battery packs for portable battery-operated equipment. Many of those chargers include a series-connected current limiting means for restricting current flow to the battery under charge.
It is well known that for proper battery charging the charging current must be conditioned, i.e., a large initial charging current is required, followed by a gradually lowering current as the internal voltage of the charged battery rises in response to increases in its charge level. To provide such conditioned current flow to the battery under charge, the circuit of the invention includes means for conditioning the input voltage to elevate it to a potential above that required for charging the battery and output voltage regulation means for controlling current flow to the battery.